P0A27: Hybrid/EV Battery Power Off Circuit
What to do
If this appeared after service work anywhere near the hybrid battery, ask whether the service plug was removed and check it was fully seated and latched — that is a genuinely common cause and a free fix. Beyond that, this is the battery's safety disconnect system: do not investigate it yourself under any circumstances.
What this code means
The circuit that disconnects the traction battery is reporting a fault.
A high-voltage battery must be disconnectable — for a crash, for service work, for a fault elsewhere in the system — and this circuit is how the vehicle knows the disconnection chain is intact and in the state it commanded. On most vehicles that chain includes the service plug (the removable link a technician pulls before working on the pack) and the feedback from the contactors that physically connect the battery to the car.
The free check comes first and it is a common story: if this code appeared after any work near the battery — an inspection, a twelve-volt battery change in the same bay, a repair that meant pulling the service plug — the plug may simply not be fully seated and latched. It is designed to break the circuit obviously when it is anything less than fully home, because ambiguously-connected is the one state a safety disconnect must never occupy. Reseating it is the entire repair in a respectable fraction of cases.
The rest of the diagnosis is the wiring and the battery module's view of its contactors, which is qualified-workshop territory.
Likely causes
Start here
Less common
- Damaged wiring harness · moderate
- Faulty battery energy control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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